Firefighters look on as two buses burn in Jerusalem. Police launched an investigation into the incident, April 18, 2016. (Israel Police)

The bus bombing in Jerusalem on Monday was a suicide terror attack orchestrated by Palestinian terror group Hamas, and several members of the cell responsible have been arrested in the West Bank, security forces revealed on Thursday as a gag order on the case was partially lifted.

The bomber who placed the explosive device on board the number 12 bus in the Talpiot neighborhood of Jerusalem was identified by the Shin Bet security agency as Abed al-Hamid Abu Srour, 19, from Beit Jala, near the West Bank city of Bethlehem.

The bomber was one of 21 people injured in the attack. He was severely wounded and died of his injuries on Wednesday.

The Shin Bet said several Hamas members from Bethlehem have been arrested in connection with the attack after an intensive manhunt by the security service, police and the IDF.

The attack marked the first suicide bombing in the wave of Palestinian terrorism that erupted last October. Hitherto, the attacks — stabbings, shootings and car-rammings — had been characterized as “lone wolf” incidents. Hamas has been encouraging attacks on Israelis, and several plots are said to have been thwarted by security forces.

The father of the bomber told Channel 2 on Thursday that he “knew nothing about his affiliation” with Hamas.

The announcement came a day after Hamas said the bomber was a member. Israel had placed the details of his identity under a gag order.

The Hamas announcement fell short of a full claim of responsibility for the attack.

Abed al-Hamid Abu Srour seen here in an undated photograph, has been named by Hamas as the person responsible for the April 18 bus bombing in Jerusalem. He died of wounds sustained in the terror attack on April 20, 2016. (Courtesy)

The terror attack broke weeks of relative calm in the city after a six-month wave of Palestinian stabbings, shootings and vehicular attacks seemed to be subsiding, and raised fears of a return to a type of violence not seen in Jerusalem for years.

Bus bombings were common during the Second Intifada, or uprising, in the early 2000s, but Monday’s attack was the first bomb targeting a bus in Jerusalem since 2011, when a British tourist was killed by a bomb planted next to a bus stop.